The present invention relates to a punching die used in the manufacture of a seal member that is wound around an exhaust gas purifier, and a method for manufacturing a seal member using a punching die.
In the prior art, an exhaust gas purification apparatus includes a filter member for trapping particulate matter (PM) suspended in the exhaust gas, a casing for accommodating the filter member, and a sheet-like seal member arranged between the filter member and the casing. The seal member is wound around the filter member, and the filter member around which the seal member is wound, is pressed into the casing (refer to JP-A-2001-316965).
The seal member is required to have the properties described below. First, the seal member must have high heat resistance to withstand high-temperature exhaust gas. Next, the seal member must prevent leakage of exhaust gas from between the filter member and the casing. Further, the seal member must prevent the filter member from falling out of the casing or from moving in the casing.
The seal member may be manufactured by processing a sheet of inorganic fibers having a predetermined shape in accordance with the size and shape of the filter member. The manufacturing processes for the seal member may include a punching process for cutting a rolled mat of inorganic fibers to a predetermined length. The punching enables a plurality of seal members to be simultaneously produced. There is a demand for further improving the productivity of seal members.